[DUG] Indy Sockets - How to Receive Asynchronously

Thu Dec 4 10:01:43 NZDT 2008

Known factors:

1. I don't know what size message will be returned.

2. The message always ends in CR LF

3. The message is always printable ASCII (not Unicode).

Date: Thu, 4 Dec 2008 09:48:52 +1300From: kyleyharris at gmail.comTo: delphi at delphi.org.nzSubject: Re: [DUG] Indy Sockets - How to Receive AsynchronouslyAlso, I guess the type of data and your message layer has a big impact on how you design your data receiver.

in my own client/servers where I control the protocol, all my messages first send an 8byte size packet.. So my read queue is constantly just doing  ASize := StrToInt( '$'+ReadString(8) ) { 8 byte hex } and this is looping.. as soon as I get a successful size I can then read the specific size of data into a message object and continue polling. If I need to send very large data like binary files,, I break it down into smaller packets encapsulated in messages using the above method.
On Thu, Dec 4, 2008 at 9:31 AM, Eric A <eaa603 at hotmail.com> wrote:

Kyley, No program design yet.  Questions: 1) Inside the thread - do I have to implement a timer event to periodically check the buffer (since there's no "data received" event)?   2) What properties do I read to determine if there's received data available?   3) Do I need to use another Indy component in conjunction with the TCPClient for the buffering etc?  Paul, I'll take a look at that site.  Are you using ICS extensively?  Thanks,Eric    

Date: Thu, 4 Dec 2008 09:21:03 +1300From: kyleyharris at gmail.comTo: delphi at delphi.org.nzSubject: Re: [DUG] Indy Sockets - How to Receive Asynchronously

Indy is blocking, so typically on the client side, you would create a waiting thread that you sit the TCPClient inside and loop a readtimeout until the resultbuffer has some data. At that point produce a local event so that your main thread can grab the TCPClient and read the information.

without knowing your actual program design and how your TCP layer interacts with your main application its hard to offer any detailed advise, sorry. 
On Thu, Dec 4, 2008 at 9:14 AM, Paul <paul.blommaerts at telenet.be> wrote:

Indy works blocking only
Use ICS instead, they work blocking or non blocking.
check www.overbyte.be

Paul

----- Original Message ----- 
From: Eric A 
To: Delphi UsersGroup 
Sent: Wednesday, December 03, 2008 8:55 PM
Subject: [DUG] Indy Sockets - How to Receive Asynchronously
I have a situation where I need to communicate with a communications server using Indy TCP sockets.   After sending the command the server returns an "OK" response with a second or two to acknowledge the acceptance of the command, however the reponse from the end device (returned via the server) may take several minutes to eventuate (or a else the sever returns a timeout message).  I need to be able to buffer the responses, be aware of when new strings arrinve, and carry on with other tasks.  This threading aspect shouldn't be an issue as I understand that Indy is naturally multitrheaded by design. I'm not familiar with using the Indy sockets and since there's no "received data event" (due to the nature of the design) I'm wondering how I capture the asynchronous responses sensibly? Does anyone have some code to show me how to use the Indy 10 TCPClient component in this way (for the receive part) ?  Its probably pretty simple but I need to get my head around it quickly. Thanks Eric

Start searching now Rental properties galore. 

_______________________________________________NZ Borland Developers Group - Delphi mailing listPost: delphi at delphi.org.nzAdmin: http://delphi.org.nz/mailman/listinfo/delphiUnsubscribe: send an email to delphi-request at delphi.org.nz with Subject: unsubscribe _______________________________________________NZ Borland Developers Group - Delphi mailing listPost: delphi at delphi.org.nzAdmin: http://delphi.org.nz/mailman/listinfo/delphiUnsubscribe: send an email to delphi-request at delphi.org.nz with Subject: unsubscribe-- Kyley HarrisHarris Software+64-21-671-821

MSN NZ Travel Get inspired - dream, research, plan and book your next holiday online with _______________________________________________NZ Borland Developers Group - Delphi mailing listPost: delphi at delphi.org.nzAdmin: http://delphi.org.nz/mailman/listinfo/delphiUnsubscribe: send an email to delphi-request at delphi.org.nz with Subject: unsubscribe-- Kyley HarrisHarris Software+64-21-671-821
_________________________________________________________________
Get inspired - dream, research, plan and book your next holiday online with MSN NZ Travel 
http://a.ninemsn.com.au/b.aspx?URL=http%3A%2F%2Ftravel%2Emsn%2Eco%2Enz&_t=771497011&_r=MSN_NZ_travel_hmtagline&_m=EXT
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://listserver.123.net.nz/pipermail/delphi/attachments/20081204/59d0ab48/attachment.html 